Adjustable hood construction for metallurgical furnace



Sept. 14, 1965 l. ROSENAK 3,205,310

ADJUSTABLE HOOD CONSTRUCTION FOR METALLURGICAL FURNACE Filed Sept. 4, 1962 2 Sheets-Sheet 1 INVENTOR. w a j ZZJLVl/JfUSEW,

Sept. 14, 1965 l. ROSENAK 15,20,810

ADJUSTABLE HOOD CONSTRUCTION FOR METALLURGICAL FURNACE Filed Sept. 4, 1962 2 Sheets-Sheet 2 INVENTOR.

frwzjwfiosemk, M W 0 5M United States Patent 3,205,810 ADJUSTABLE H091) CONSTRUCTION FOR METALLURGICAL FURNACE Irwin Rosenalr, Munster, Ind, assignor to Inland Steel Company, Chicago, lit, a corporation of Delaware Filed Sept. 4, 1962, Ser. No. 221,262 8 Claims. (Cl. 98-115) This invention relates to an adjustable hood construction for a metallurgical furnace and more particularly to an adjustable hood construction for an oxygen steelmaking furnace.

In the so-called LD oxygen steelmaking process, and in similar metallurgical refining processes, a tiltable vessel or furnace having a comparatively large mouth is frequently employed for carrying out the refining reac tions. The large mouth is advantageous in that rapid charging of the furnace is facilitated. A large mouth furnace is considered by some experts to be undesirable, however, from the standpoint that at certain times dur' ing an oxygen steelmaking operation, a large mouth may allow excessive amounts "of air to infiltrate into the furnace and across the surface of the molten metal. Such air infiltration may cause an undesired increase in the nitrogen content of the steel.

Moreover, in oxygen steelmaking installations, or the like, as heretofore used, it has been customary to mount an exhaust hood or duct over the mouth of the refining vessel, the hood or duct having an exhaust fan for removing gases and fumes evolved during the refining process. in many such installations the inlet opening of the hood is substantially larger than the mouth of the refining vessel so as to provide a fixed annular opening therebetween. As a result, the total gas volume drawn through the hood by the fan includes the effluent gases and fumes from the refining vessel and also a certain amount of air drawn in through the aforementioned annular opening. However, inasmuch as the size of this annular opening is fixed, the operator has no means of regulating the total volume of gas passing through the hood and therefore cannot always select the most economical operation for the exhaust fan.

Accordingly, one object of the invention is to provide a novel and improved adjustable hood construction for a metallurgical furnace which overcomes the above-discussed disadvantages.

A further object of the invention is to provide a novel and improved adjustable hood construction adapted for use with a metallurgical furnace having a wide mouth for preventing excessive air infiltration into the furnace during a refining operation.

A more particular object of the invention is to provide a novel adjustable hood construction for use with an oxygen steelmaking converter having a large mouth and wherein the hood provides certain advantages of a small mouth furnace.

A specific object of the invention is to provide a novel adjustable hood construction adapted for use with an oxygen steelmaking furnace having a stationary exhaust hood, whereby to prevent excessive air infiltration into the furnace and also to permit adjustment of the rate of air introduction into the stationary exhaust hood.

Another object of the invention is to provide an adjustable hood construction adapted for use in cooperation with a metallurgical furnace having a stationary exhaust hood, whereby to regulate the introduction of air into the exhaust hood.

Other objects and advantages will become apparent from the following detailed description and accompanying sheets of drawings, in which:

FIG. 1 is a side elevational view, with some parts in ifififilii Patented Sept. 14, 1965 section, of the mouth of a metallurgical furnace, and showing a stationary hood disposed above the furnace mouth and an adjustable hood construction embodying the features of the present invention and disposed in an elevated position with respect to the furnacemouth;

FIG. 2 is a horizontal sectional view taken along the line 22 of FIG. 1;

FIG. 3 is a vertical sectional view, similar to PEG. 1, and showing the adjustable hood construction of the pres ent invention in an operable position with respect to the mouth of the furnace; and

FIG. 4 is a view similar to FIG. 3, but showing the parts of the hood construction in another operating position.

Briefly described, the present invention contemplates, in its specific aspects, a novel adjustable hood construction adapted for use with an oxygen steelmaking furnace for preventing excessive air infiltration into the furnace during a processing operation and for controlling the size of an annular passage through the hood and around the mouth of the furnace for controlling air flow therethrough. Such control of the air flow serves to control the temperature and flow of gases in the hood. .In its broader aspects, the present invention contemplates an adjustable hood construction which, when disposed adjacent the mouth of a comparatively large mouthed vessel, such as a furnace, in effect converts the vessel into one having a smaller mouth for minimizing air infiltration into the vessel. The hood is also generally operable to control temperature and flow conditions of gases exhausting through the hood.

An adjustable hood construction embodying the features of the present invention thus contemplates an inner tubular hood member that is adapted to be disposed closely adjacent or in engagement with the open mouth of an associated furnace such that the inner member forms a continuation of the furnace mouth. The inner hood member tapers inwardly from the end thereof adjacent the furnace mouth and, in effect, reduces the size of the furnace mouth. An outer tubular hood member of somewhat greater size than the inner hood member is disposed around the latter to define an annular passage therebetween. The remote or upper end of the outer hood memher is adapted to extend into the open end of a fixed exhaust duct or hood which receives and withdraws gases evolving from the furnace during a refining operation. The lower portion of the outer hood member maybe flared to provide a shirt for directing gases escaping between the furnace mouth and inner hood member into the annular passage between the inner and outer hood members.

Means is provided for shifting or elevating the outer hood member with respect to the inner hood member to thereby control the size of the annular passage between the members and thus the quantity of air which will be drawn therethrough and around the upper or remote end of the inner hood member during the processing operation.

Means is also provided for shifting or elevating both the inner and outer hood members away from the mouth of the furnace to permit tilting of the furnace for charging or tapping.

In the drawings an adjustable hood construction It) embodying the features of the present invention is illustrated in operable relation with respect to the mouth 11 of a converter or furnace 12 and a stationary exhaust duct or hood 13. The furnace 12, in the present instance, is of the tiltable type adapted for use in the socalled LD oxygen steelmaking process and thus has a comparatively large mouth 11 to facilitate rapid charging, to increase the strength of the ceramic lining, and to provide better slag separation. The large mouth 11 also facilitates insertion into the furnace of an oxygen lance 14 which is mounted in the stationary duct or hood 13.

The fixed duct or hood 13 comprises a lower cylindrical portion 16, into which a portion of the adjustable hood extends, and an upwardly inclined duct portion 17 connected at its lower end to the cylindrical portion 16. The inclined portion 17 is provided with a fitting 18 for slidably receiving the oxygen lance 14 and guiding the latter during movement thereof into and out of the furnace 12 when the charge is being blown. The remote upper end (not shown) of the inclined hood portion 17 is connected to a low-pressure exhaust source, such as a fan, for removing fumes and waste gases during a processing operation.

From the foregoing, it will be apparent that if only the stationary duct or hood 13 were employed to receive gases escaping from the mouth 11 of the furnace 12 during a refining operation, there would have'to be some spacing between the furnace mouth 11 and the lower end of the duct or hood 13 in order to permit tilting of the furnace for charging or tapping. Such spacing or gap might permit air to enter the furnace through the comparatively wide mouth 11 as a result of inspiration due to the high velocity of the oxygen stream through the lance 14. Such air infiltration is undesirable, particularly during an oxygen steelmaking operation, as the result may be to cause the steel to absorb excessive amounts of nitrogen. The adjustable hood construction 10 of the present invention overcomes this disadvantage and provides certain other advantages, as hereinafter described.

The adjustable hood construction 10 generally comprises an inner tubular hood member 21, which is adapted to engage the mouth 11 of the furnace when the hood is in place, and a somewhat larger outer tubular hood member 22 which encloses the inner hood member 21 and is movable with respect thereto. The inner hood member, in this instance, is generally frusto-conical in shape and has its lower end 23 substantially equal in size to the mouth 11 of the furnace 12 so that when the hood member 21 is operably disposed closely adjacent or in engagement with the furnace mouth 11, the former becomes a continuation of the mouth. The upper end, indicated at 24, of the hood member 21 is substantially smaller than the end 23 so that when the member 21 is operably disposed adjacent the furnace mouth 11, the upper end 24 in effect becomes the mouth of the furnace. Thus, with the inner hood member 21 disposed closely adjacent or in engagement with the furnace mouth 11, air infiltration into the furnace is minimized. The inner surface of the hood member 21 may be provided with a suitable refractory lining, indicated at 25, to protect the hood member.

The outer hood member 22 comprises an upper cylindrical portion 27 having a diameter smaller than that of the inner diameter of the cylindrical portion 16 of the stationary duct or hood 13 to permit the portion 27 to telescope therein. The cylindrical portion 27 has an axial length sufiicient to accommodate movement of the member 22 throughout a range of positions including the lower and upper limit positions of the member 22 as illustrated in FIGS. 3 and 4, respectively.

The lower portion, indicated at 28, of the outer hood member 22 is flared outwardly to provide a skirt having an angle of taper substantially equal to that of the angle of taper of the inner hood member 21. The annular inner surface of the skirt 28 and outer surface of the hood member 21 together define an annular passage 30 therebetween.

As herein illustrated, the stationary duct or hood 13 and the inner and outer adjustable hood members 21 and 22 are shown as having spaced outer wall portions to permit passage of water or other cooling medium through the passages 26 by means of suitable pipes or other fluid connections (not shown). However, it should be understood that such cooling provisions may be omitted in some instances.

The annular passage 30 is adapted to be varied in size upon raising or lowering of the outer hood member 22 relative to the inner hood member 21 thus controlling the air flow therethrough and consequently the fiow around the upper end 24 of the inner hood member which forms a continuation of the furnace mouth 11. Control of the air flow through the passage 30 controls the combustion of CO at the upper end 24 of the inner hood member. Thus, the temperature of the gases exhausting through the duct 17 of the stationary duct or hood 13 may be controlled by the air flow through the passage 30 and the quantity of gas discharging through the duct or hood 13 may be maintained within limits which can best be accommodated by the fan at the remote end of the duct 17. Accordingly, the adjustable hood construction 10 enables the operator to control the gas volume passing through the exhaust hood and thereby allows the operator to select the most economical operation for the available fan.

The provision of the flared skirt 28 is also advantageous in that any gaseous products leaking at the interface between the furnace mouth 11 and the adjacent end 23 of the inner hood member 21 are directed into the flow of air in the annular passage 30.

In order to permit raising or lowering of the entire hood construction 10 to a position above or remote from the furnace mouth 11, as indicated in FIG. 1, to thereby permit the furnace 12 to be tilted either for a charging or tapping operation, suitable lifting means is provided. Such means in the present instance comprises three circumferentially spaced radially outwardly extending lugs 31 secured to the inner hood member 21, as by welding or the like. The lugs 31 extend loosely through upright slots 32 in the skirt 28 of the outer hood member 22, and the slots 32 are dimensioned so that when the outer hood member 22 is supported on the lugs 31, as in FIGS. 1 and 3, the lower edge of the skirt 28 is substantially co-planar with the lower end face of the inner hood member 21. The outer ends of the lugs 31 may be provided with openings to facilitate connection of rods or cables 33 which effect actual raising or lowering of the hood construction 10.

In order to effect the aforementioned relative movement between the inner and outer hood members 21 and 22, respectively, the skirt portion 28 of the outer hood member 22 is also provided with three circumferentially spaced radially outwardly extending lugs 36 which are interposed between the lugs 31. The outer ends of the lugs 36 are provided with openings, in the manner of the lugs 31, to facilitate connection of rods or cables 37 which may be utilized to effect raising or lowering of the outer hood member 22.

Thus, the rods or cables 33 and 37 permit raising and lowering of entire hood construction 10 with respect to the furnace 12 during charging or tapping of the furnace and adjustment of the position of the outer hood member 22 relative to the inner hood member 21 to thereby control the size of the annular passage 30 for the purposes heretofore described.

While only one embodiment of the invention has been herein illustrated and described, it will be understood that modifications and variations thereof may be effected without departing from the scope of the invention as set forth in the appended claims.

I claim:

1. An adjustable hood construction adapted for use with a metallurgical furnace, such as an oxygen steelmaking furnace, having a relatively large mouth, comprising an inner tubular hood member having one end of substantially the same size as the mouth of said furnace and another end of lesser size, means for positioning said one end substantially in engagement with the mouth of said furnace so that said inner hood member forms a continuation of said furnace mouth, an outer tubular member of greater size than said inner hood member and disposed around the latter, said inner and outer hood members defining a passage therebetween, and means for supporting said inner and outer hood members and for effecting relative movement therebetween for varying the size of said passage.

2. The adjustable hood construction of claim 1 further characterized in that said inner hood member tapers inwardly from said one end to said other end, and said outer hood member includes an outwardly flaring skirt having an angle of taper substantially equal to that of the angle of taper of said inner hood member.

3. An adjustable hood construction according to claim 1 further characterized in that said means for effecting relative movement between said hood members comprises outwardly extending lug means carried by said outer hood member, said lug means providing a connection point for means for moving said outer hood member relative to said inner hood member.

4. An adjustable hood construction according to claim 2, further characterized in that said inner hood member is provided with outwardly extending lug means for connection to a moving means, and said skirt is provided with slot means for receiving said lug means, said slot means permitting said inner hood member to telescope within said outer hood member to a position enclosing said inner hood member.

5. An adjustable hood construction adapted for use with a metallurgical furnace, such as an oxygen steelmaking furnace, having a relatively large mouth, comprising a generally conically tapered inner tubular hood member having its larger end substantially equal in size to the mouth of said furnace, the smaller end of said inner hood member being substantially smaller than the mouth of said furnace, means for positioning the larger end of said inner hood member closely adjacent said furnace mouth so that said larger end forms a continuation of said furnace mouth, an outer tubular hood member of greater size than said inner hood member, said outer hood member being generally cylindrical at one end and having an outwardly flared skirt at its other end, said inner and outer hood members defining an annular passage therebetween, said one end of said outer hood member being adapted to extend into an exhaust zone for inducing an air flow through said annular passage, and means for supporting said inner and outer hood members and for shifting said outer hood members relative to said inner hood member for varying the size of said passage.

6. In combination, a tiltable metallurgical furnace having a relatively large mouth at its upper end, a stationary exhaust hood disposed in elevated relation above the mouth of said furnace, and aadjustable hood means interposed between said furnace and said exhaust hood, said adjustable hood means comprising an inner tubular hood member having a relatively large lower end adapted to fit against said mouth and a relatively smaller upper end, an outer tubular hood member surrounding said inner hood member and defining a generally annular passage therebetween, the upper end of said outer hood member extending adjustably into said exhaust hood whereby to provide for intake of outside air through the lower end of said passage into said exhaust hood, and means for raising and lowering said hood members relative to said furnace and for regulating the relative positions of said inner and outer hood members.

7. The combination of claim 6, further characterized in that said inner and outer hood members have outwardly flared lower end portions, the flared lower end portion of said outer hood member having a plurality of slots and the flared lower end portion of said inner hood member having lugs extending outwardly through said slots for connection to cables or the like for raising and lowering both of said hood members.

8. The structure of claim 7, further characterized in that said outer hood member is also provided with lug means for connection to additional cables or the like for raising and lowering the outer hood member relative to the inner hood member.

References Cited by the Examiner UNITED STATES PATENTS 457,910 8/91 Dickenson 98-115 XR 1,434,313 10/22 Prat 98--43 2,125,454 8/38 Marshall 98-41 2,862,701 12/58 McFeaters 981 15 XR 3,026,102 3/62 McFeaters 266- ROBERT A. OLEARY, Primary Examiner. 

1. AN ADJUSTABLE HOOD CONSTRUCTIN ADAPTED FOR USE WITH A METALLURIGICAL FURNACE, SUCH AS AN OXYGEN STEELMAKING FURNACE, HAVING RELATIVELY LARGE MOUTH, COMPRISING AN INNER TUBULAR HOOD MEMBER HAVING ONE END OF SUBSTANTIALLY THE SAME SIZE AS THE MOUTH OF SAID FURNACE AND ANOTHER END OF LESSER SIZE, MEANS FOR POSITIONING SAID ONE END SUBSTANTIALLY IN ENGAGEMENT WITH THE MOUTH OF SAID FURNACE SO THAT SAID INNER HOOD MEMBER FORMS A CONTINUATION OF SAID FURNACE MOUTH, AN OUTER TUBULAR MEMBER OF GREATER SIZE THAN SAID INNER HOOD MEMBER AND DISPOSED AROUND TE LATTER, SAID INNER AND OUTER HOOD MEMBERS DEFINING A PASSAGE THEREBETWEEN, AND MEANS FOR SUPPORTING SAID INNER AND OUTER HOOD MEMBERS AND FOR EFFECTING RELATIVE MOVEMENT THEREBETWEEN FOR VARYING THE SIZE OF SAID PASSAGE. 